WaterMarc and Peninsula Aquatic Recreation Centre record high levels of yeast, mould bacteria, Herald Sun analysis reveals

High levels of bacteria, including yeast and mould, have been found in Melbourne swimming pools as Victorian swimmers battle a parasitic gastro outbreak at public pools.

The Herald Sun tested the pool water from 13 aquatic centres. Picture: Supplied.

High levels of bacteria — including yeast and mould — have been found in some of Melbourne’s most popular suburban pools, as the state battles a major gastro outbreak stemming from local aquatic centres.

Water testing on 13 of Melbourne’s largest kids’ pools, conducted exclusively by the Herald Sun through an independent laboratory, assessed e-coli and other harmful bacteria levels.

WaterMarc in Greensborough and the Peninsula Aquatic Recreation Centre (PARC) in Frankston recorded non-compliant bacteria readings well above the legislated satisfactory levels.

WaterMarc had the highest heterotrophic plate count (HPC) reading of 160 CFU/ml — a measure of bacteria including yeast and mould.

The maximum satisfactory level is 100 CFU/ml, according to the Victorian Public Health and Wellbeing Act.

The Herald Sun understands professional laboratories recommend urgent further testing for any results above 200 CFU/ml.

WaterMarc had the highest HPC levels of the 13 pools tested. Picture: Andy Brownbill

PARC — which in FY24 saw more than 895,000 visits — recorded bacteria levels at 120 CFU/mL.

A Banyule Council spokeswoman said WaterMarc conducted laboratory testing monthly, and all results over the past five years — including one on January 15 — were compliant.

“If any pool water test returns results that are inconsistent with regulation levels, measures are taken immediately to ensure public safety,” she said.

“This can include short-term closure of a pool – for example if the chlorine level is too high or too low.”

She added unsatisfactory microbiological testing would result in redoing a test and council conducting an investigation.

Peninsula Aquatic Recreation Centre (PARC) recorded unsatisfactory bacteria levels in its pool water. Picture: Supplied.

Peninsula Leisure chief executive Kath Thom said PARC last undertook microbiological testing in December 2024 and recorded an HPC of 3 CFU/ml — significantly lower than when the Herald Sun tested just weeks later.

“Microbiological testing that Peninsula Leisure has undertaken has not flagged any noncompliance, and historically, PARC’s results … have been within compliant ranges each quarter,” she said.

“Peninsula Leisure is committed to maintaining the highest standards of water quality and safety for patrons across all of its facilities.”

Ms Thom said PARC’s water management plan was aligned with state legislation and included frequent tests, active monitoring and treatment protocols where required.

“Additionally, we take proactive steps to raise awareness about healthy swimming practices to ensure our pools remain clean and safe,” she said.

The Herald Sun completed both chemical and microbiological testing on water from 13 Melbourne pools. Picture: Erin Constable

The remainder of the pools tested — which included GESAC, Knox Leisureworks, Splash (in Craigieburn) and Aquapulse, among others — came back with clean bills of health with the next highest HPC recording just half of the legislated maximum.

The Herald Sun also conducted chemical testing on the pools’ pH and chlorine levels, with all centres found to be compliant.

Public Health Association chief executive Terry Slevin said both the pool operators and the public played a role in keeping aquatic centres clean and safe.

“Obviously it is up to the pool operators and how diligent they are with regular testing and cleaning their pools,” he said.

“But it’s the public’s responsibility to take precautions, especially when they are ill, when they are using public pools.”

Mr Slevin said the “vast majority” of people who used swimming pools did not come away sick.

“It is all about balancing the benefits of swimming, which are very high, and the risk of getting crook, which is quite low,” he said.

The results come as at least 87 cases of the parasitic gastro infection cryptosporidiosis, which causes watery diarrhoea and stomach cramps for several weeks, have been recorded in Victoria so far in 2025, prompting health authorities to urge those sick to avoid public swimming pools for at least a fortnight after symptoms end.

This follows a record 2349 cases reported to the Department of Health in 2024 — a 233 per cent increase on the previous year.

Cryptosporidiosis is a parasitic gastrointestinal disease that can be spread through public pools. Picture: Supplied.

Chief health officer Tarun Weeramanthri said chlorine killed most germs but some, such as cryptosporidium, were highly resistant to the chemical at normal concentrations and could present a health risk.

“It’s important to remember that you remain infectious for several weeks after your diarrhoea stops,” he said.

Dr Weeramanthri said swimmers should avoid the pool for two weeks after their symptoms ceased, shower with soap before using the pool, avoid swallowing pool water and only change nappies in designated areas.